Steel retainer



April 3, 1928.

W. PRELLWITZ STEEL RETAINER Filed Nov. 12. 1926 I N VEN TOR.

Ty/221%?! m BY 7 HIS ATT RNEX Patented Apr. 3, 1928.

. UNITED STATES WILLIAM PRELLWITZ, 0F EASTON, PENNSYLVANIA, ASSIGNOR T0 INGERS0LL BAND COMPANY, OF JERSEY CITY, NEW JERSEY,

A CORPORATION OF NEW JERSEY.

STEEL RETAINER.

Application filed November 12,1926. Serial No. 147,951.

limiting the distance which the drill steel.

may extend into" the percussive tool.

The objects of the lnventlon are to insure retention of the working implement in the rock drill and to construct a rugged retaining device for rock drill steels which may be cheaply manufactured and which comprises only a few simple parts.

Other objects will appear hereinafter.

The invention is shown in one of its pre ferred forms in the accompanying drawings, in which Figure 1 is a side View in elevation of a front end of a rock drill having the invention applied thereto,

Figure 2 is a front View inelevation of a portion of a rock drill showing the manner in which the retainer is held against oscillation as well as against contact with the front head of the drill, and

Figure 3 is a sectional View taken through Figure 1 on the line 33 looking in the direction of the arrows.

Referring more particularly to the draw ings, A represents the front end of a cylinder and B a front head, in this instance held in spaced relation with respect to the cylinder A by a front cylinder washer C; Lugs D are carried by'the front head 13 to re ceive spring pressed side bolts E whereby the front head and other casing parts, such as the cylinder A and the front cylinder asher G maybe clamped securely in sombled' position.

In the front end of the front head B is formed a recess F into which extends loosely a collar G of a drill steel H. A shank J of the drill steel H extends rearwardly of the collar G into the front head to receive he blows of the hammer piston (not shown).

In the present instance the front head B is provided with oppositely disposed trunnions K preferably offset from the longitudinal axis of the front head. The trunnions K in this instance resemble truncated cones and are so arranged on the front head that the largest diameter is at the outer free ends of the trunnions. In this way, a tapered or inclined perimetrin surface is provided for a purpose to be described more fully hereinafter.

Means are provided for preventing ejcc tion of the drill steel H from the front head B. To this end a yoke L arranged to partly encircle the drill steel H forwardly of the collar G and has rearwardly extending side arms 0 carrying at their rearward or free ends closed'loops P. The front ends Q of the loops P are so shaped as to conform to the shape of the trunnions K and the rearward ends R of the loops may be former; to any convenient curve.

The side arms 0 and the loops P are formedof a single piece of wire of any suit able cross sectional area necessary to withstand the severe usage to which devices of this type are subjected. Preferably, the free ends of the side arms are slightly contracted toward each other so that when the yoke is in position on the front head aslight spring effect will be obtained tending to press the side arms against the front head.

The shock absorbing or cushioning means in this instance comprises coil springs S in-' terposed between the rearward surfaces the trunnions K and the rearward ends of the loops P. These springs S are preferably of a suitable length to enable then'i to exert a constant pressure in rearwardly or up Wardly direction for holding the front ends .Q, of the loops firmly against the trunnions K. r y

To the end that the springs S may be conveniently held in operative position in the loops P, spring seats T are provided for the rearward ends of the s 'nrings and are grooved as at U to engage the inner sin'li'acc of the rearward ends R of the loops 1? for preventing relative transverse movement between the spring seats T and the loops P. Preferably projections V are formed on the spring seats T to extend into the rearward. ends of the springs.

Suitable supports are provided for the front ends of the springs S in the form of bearings. having reduced extensions or tips X which extend into the front ends of the springs. The bearings W are recessed as at Y to conform to the conical surfaces ofvthe trunnions K for preventing outward movement of the hearings on the trunnions, that is, movement of the bearings in the direction of the outer enlarged end ofthe trunnions. V

In order that the yoke L may be normally held in retaining position, lugs Z are formed on opposite sides of the front head B and provided with grooves b to receive' the side arms 0. The said grooves in this instance are rather shallow to enable the side arms 0 to be readily rocked into and out of engagement therewitl'i. {The lugs Z are preferably formed rearwardly of the trunnions Kand in addition to their functions of preventing free ioscillation of the yoke L on the trunnions K also hold the side arms 0 free of the front head 13 throughout their lengths. In thiswaythc yoke, will be protected against breakage which frequently happens due to the impact of the side arinsagainst the front head whenever the drill steel strikes the yoke.

asseinhling thedcvice on the rock drill, the side arms 0 maybe spread to. enable the loops P to be plaeedabout the trunnions K. Thereafter the bearings l/V may be placed on the trunnionsand the springs ,S and spring seats may then be placed in their proper relative positions.

springs S may then be compressedsnilicintly to enable the springseats T to bepressed in engagement with the rearward ends It of the loops P. l

During the operation of the device whenever it is desired to remove the drill steel from the front head 13, the yoke L be rocked out of the path of the collar G of the drill steel, thus provlding a free path for the removal of said drill steel.

After anotherfdrill steel has again been-in sertedlin the front head, the yoke may be rocked to its retaining position. In this position the side arms 0 will engage the grooves b and,due tothe inherent resiliency of the yoke, the side arms Will be held firmly in engagement withsaid rooves. However, when the yoke is rodked about the "trunnions the side armswill spread readily to enable them to pass over the endsofthe lugs Z. 7

I claim: 1. A drill steel retainer comprising a front head having trunnions, said-trunnions having inwardly tapering bearing surfaces, hearings on said trunnions, said bearings having inwardly taperingbearing surfaces,

cooperating with: said inwardly tapering bearing surfaces on said trunnions and hav .ing spring centering tips, springs centered on said bearings, spring seats having centering tips carried said springs, a retainer in the form of looped resilient memtrunnions tend to press inwardly towards the sides of the front head while the arms of the retainer swing free and clear of'the front end of the front head, and retaining lugs at each side of thefront head cooperating withithe retainer rearwardly of thetrunnions.

A drill steel retainer comprising a front head having trunnions, said trunnions having inwardly tapering bearing surfaces, hearings onsaid trnnnions, said bearing having inwardly tapering bearing surfaces cooperating with said inwardly tapering bearing surfaces on said trunnions and-ihaving spring centering tips, helicalsprings centered on said centering tips, spring seats having centering tips and grooves fat the opposite ends, carried by sa dfsprlngs, a retainer in the form of a looped resilient .inember having aflU' shaped portion at its forward end embracingthe drillsteel, the free ends of thearms of sa d retainer be ingbent to form elongated loops passing" around the trunnions and over the spring seats at each side. of the front head and lugs at each side of the frontghead having sloping sides and a groove at the apex to cooperate with said retainerto ,hold the retainer in a normally retainingposition. V

In testl nony whereof I have signed this specification. a. a I NVILLIAM PRELLXVIIIZ. 

